Iks is a mysterious individual encountered by the protagonist in the desert, exhibiting a calm and trusting persona that often appears harmless. His unknown origins and intentions cause concern for the governing powers. He possesses significant healing abilities, mending wounds through touch, though these powers have limitations and cannot save a well-loved character from the edge of death.

It is later revealed that Iks is an extraterrestrial visitor sent to observe Earth. His purpose is to act as an observer, not to interfere, and he is there to make a decision about the planet. Identified as the Arbitrator, he is tasked with observing humanity and the world post-devastation. To understand the world more, he joins the protagonist on her travels.

Throughout the journey, Iks develops a deep connection with the protagonist. He contracts with her to accompany her for most of her travels to see the world through her eyes. His constant cheerful attitude and lack of disclosure about himself are part of his non-interference directive. Despite this, he forms a strong bond and eventually falls in love with her, admitting his feelings just before the final events. This marks a significant personal development from a detached observer to an emotionally involved individual.

Iks is perceived by some other characters as a romantic rival. His relationship with the protagonist is a point of contention, particularly with another character who sees him as such. His presence and the mystery surrounding him are central to the unfolding events, impacting the protagonist's journey and the broader narrative.

Near the story's conclusion, his true nature and advanced abilities are fully displayed. He is shown to be immune to bullets, which are absorbed into an energy barrier around him, revealing his capabilities as a sufficiently advanced alien. His role culminates in his decision as the Arbitrator, which is influenced by his experiences and emotional connections on Earth.